1. Field of the Invention
The invention relates to a urine sugar detecting device, and a method of fabricating the same.
2. Description of the Related Art
Many urine sugar detecting devices have been suggested so far. For instance, Japanese Unexamined Patent Publication No. 8-193969 has suggested a device for electrically, chemically detecting glucose, and Japanese Patent Publication No. 8-23545 has suggested an enzyme electrode to be used for a glucose sensor.
For another instance, Japanese Unexamined Patent Publication 5-72172 has suggested an enzyme electrode to be used for a urine sugar detecting sensor. FIG. 1 illustrates the enzyme electrode suggested in the Publication. The illustrated enzyme electrode is fabricated as follows.
First, a platinum layer is formed on an insulating substrate 1 by sputtering. Then, the platinum layer is patterned by photolithography and etching steps to thereby form operation electrodes and reference electrodes. Each of the operation and reference electrodes is comprised of a sensitive portion 2a, a lead portion (not illustrated), and a connection portion 2b.
Then, dip coating is applied to the insulating substrate 1 to thereby form an enzyme film 3 over the insulating substrate 1 except the connection portions 2b. Thereafter, the insulating substrate 1 is divided into enzyme electrodes.
In the enzyme electrode illustrated in FIG. 1, dip coating is applied to the insulating substrate 1 in order to form the enzyme film 3. However, the dip coating is accompanied with problems that the dip coating cannot be applied to a plurality of substrates at a time, and hence, is not suitable for mass-production of enzyme electrodes, and that it is quite difficult for the dip coating to uniformize film quality and film thickness.
To solve these problems, Japanese Patent Publication No. 8-16669 has suggested a method of patterning an enzyme film in a region other than contact electrodes by photolithography. In this method, lift-off is carried out using a photoresist film. This method is carried out as follows.
First, contact electrodes are formed on a substrate. Then, a photoresist film is formed over the substrate by spin coating. Then, the photoresist film is removed in a region other than contact electrodes by photolithography.
Then, an enzyme film is formed over the substrate by spin coating. Then, the residual photoresist film is dissolved by organic solvent to thereby remove the enzyme film on the contact electrodes.
According to the method suggested in Japanese Patent Publication No. 8-16669, a plurality of substrates can be treated at a time, because a photoresist film can be applied to those substrates at a time by spin coating. Hence, the suggested method is suitable for mass-production of enzyme electrodes, and, in addition, has an advantage that film quality and film thickness can be readily uniformized.
However, the method suggested in Japanese Patent Publication No. 8-16669 needs to carry out a photolithography step. In other words, the method needs a particular apparatus for carrying out photolithography, and hence, is accompanied with a problem that it is not possible to shorten a time for fabricating an enzyme electrode.
In addition, the necessity of preparing a photolithography apparatus increases fabrication costs.